Problem: William is 72 years old and Umaima is 12 years old. How many years will it take until William is only 4 times as old as Umaima?
Solution: We can use the given information to write down an equation about how many years it will take. Let $y$ be the number of years that it will take. In $y$ years, William will be $72 + y$ years old and Umaima will be $12 + y$ years old. At that time, William will be 4 times as old as Umaima. Writing this information as an equation, we get: $72 + y = 4 (12 + y)$ Simplifying the right side of this equation, we get: $72 + y = 48 + 4 y$ Solving for $y$ , we get: $3 y = 24$ $y = 8$.